Prior art methods for the radiography of the dental, jaw, and skull regions, such as the intraoral radiography, panoramic tomography, as well as the linear and polydirectional tomographies, visually perform the alignment of the recording field and object layer onto the patient only on the basis of the external structures of the patient only on the basis of the external structures of the patient by means of light beam markers, which indicate the central ray of the X-ray beam and the location of the object layer. In intraoral radiography, however, the selection of the object region is done purely on the basis of visual inspection. In addition, the different regions to be radiographed by using the aforementioned techniques are recorded on separate films.
Such panoramic equipment, which is most generally used for extraoral radiography of the jaws and the dentition onto a moving film by means of a thin, rotating X-ray beam, are also capable of recording the entire radiographed object onto a single sheet of film. A facility of recording a partial image of the object has only been possible by stopping the exposure. However, any advantage from stopping the exposure is only gained in a situation where the exposure has been started from such a part of the object which is of primary interest. In principle, it has also been possible to delineate the X-ray beam so as to expose, for instance, only the upper jaw with the upper teeth or the lower jaw with the lower teeth, onto the upper or lower part of the film sheet while shielding the lower or upper part of the film from exposure, respectively. In addition, these apparatuses employ fixed equipment specific projections in both the horizontal and vertical directions.
Also known in the art is a radiographic apparatus (FI patent application No. 79 0555), in which a part of the film sheet is used for recording the dental arch while the rest of the film is used for recording the temporo-mandibular joint in a predetermined image plane.
Panoramic radiography apparatuses known in the art are not capable of changing the projection in order to optimize the recording of an anatomic detail or for solving a diagnostic problem involving the detail. In practice, this often leads to excessively comprehensive exposures and poor radiographic hygienics relative to the task, as well as to promoting a relaxed acceptance of limited diagnostic information even if the solution to the problem is known to require the object to be recorded in several projections. In addition, the localization of the desired object to be recorded is cumbersome, or may be impossible, with the use of prior art panoramic radiography equipment.